I don’t believe the article.
Ukrainians can at best bleed Putin until he just takes the black sea coast and Donbas. No way can they do any better
Ukrainians can kill Russians till they leave Ukraine.
Then think of small, mobile Ukrainian units, arms caches everywhere, etc., plus bad Russian logistics, ill maintained equipment, untrained Russian soldiers and an air force without precision munitions and a low sortie rate and bad maintenance.
Putin bought lots of pretty, new equipment with no support, spare parts and inadequate training. The Russians make advances, get bogged down, and then get picked off and knocked out.
They may not even be able to seize all the Black Sea areas.